Screening demulsifiers for crude oil-water emulsions

ABSTRACT

Certain implementations of the subject matter can be implemented as a method of screening demulsifiers for live crude oil-water emulsions. A live emulsion of a hydrocarbon sample and a water sample is flowed through a capillary viscometer. The live emulsion includes dissolved gases retrieved from a hydrocarbon-carrying reservoir. While flowing the live emulsion through the capillary viscometer, a demulsifier sample is flowed through the capillary viscometer. The demulsifier sample causes breakdown of the live emulsion. Using the capillary viscometer, change in a viscosity of the live emulsion over time resulting from the breakdown of the live emulsion due to the demulsifier sample is measured. Multiple images of the breakdown of the live emulsion over time are captured. A strength of the live emulsion is classified based, in part, on the change in the viscosity of the live emulsion over time and on the plurality of images.

TECHNICAL FIELD

This disclosure relates to emulsions of hydrocarbon liquids and waterand, more particularly, to analyzing effects of demulsifiers onemulsions of hydrocarbon liquids and water.

BACKGROUND

Hydrocarbons entrapped in subsurface reservoir rocks can be produced(that is, raised to the surface). Hydrocarbons are seldom producedalone; rather, they are often commingled with water which is also in thesubsurface reservoir rocks. The produced water is generally present inthe form of emulsions, which can present operational challenges duringhydrocarbon production and processing, for example, in gas-oilseparation plants (GOSPs). Untreated or improperly treated emulsions canresult in issues such as occasional tripping of separation equipment inGOSPs, production of off-spec crude oil, increased pressure in flowlines, corrosion, and catalyst poisoning in downstream processingfacilities, to name a few. To avoid these issues and to meet crude oilspecifications for transportation, storage and export, emulsions have tobe treated. Treating an emulsion can include mixing chemicals calleddemulsifiers to the emulsions to break or separate the emulsions.

SUMMARY

This disclosure describes techniques relating to evaluatingeffectiveness of demulsifiers to break hydrocarbon liquid-wateremulsions. As used in this disclosure, live hydrocarbon is hydrocarboncontaining dissolved gas in solution that may be released from solutionat surface conditions. Dead hydrocarbon is hydrocarbon at sufficientlylow pressure that it contains no dissolved gas. An emulsion is adispersion (droplets) of one liquid in another immiscible liquid. Thephase that is present in the form of droplets is the dispersed orinternal phase, and the phase in which the droplets are suspended iscalled the continuous or external phase. For produced oilfieldemulsions, one of the liquids is aqueous and the other is crude oil. Asused in this disclosure, a live emulsion sample is a sample obtainedfrom a surface processing facility, or a production stream, orsubsurface reservoir rock that includes live hydrocarbons as thedispersed phase and water as the continuous phase.

Certain implementations of the subject matter can be implemented as amethod. A live emulsion of a live hydrocarbon sample and a water sampleis flowed through a capillary viscometer. The live hydrocarbon sampleincludes dissolved gases retrieved from a hydrocarbon-carryingreservoir. While flowing the live emulsion through the capillaryviscometer, a demulsifier sample is flowed through the capillaryviscometer. The demulsifier sample is capable of causing breakdown ofthe live emulsion. Using the capillary viscometer, change in a viscosityof the live emulsion over time resulting from the breakdown of the liveemulsion due to the demulsifier sample is measured. Multiple images ofthe breakdown of the live emulsion over time are captured. A strength ofthe live emulsion is classified based, in part, on the change in theviscosity of the live emulsion over time and on the plurality of images.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The demulsifier sample is a firstdemulsifier sample. The live emulsion is a first live emulsion. A secondlive emulsion of the hydrocarbon sample and the water sample is flowedthrough the capillary viscometer. While flowing the second live emulsionthrough the capillary viscometer, a second demulsifier sample is flowedthrough the capillary viscometer. Using the capillary viscometer, changein a viscosity of the second live emulsion over time resulting from thebreakdown of the live emulsion due to the demulsifier sample ismeasured. Multiple images of the breakdown of the second live emulsionover time are captured.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A concentration of the seconddemulsifier sample is different from a concentration of the firstdemulsifier sample.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A temperature at which the seconddemulsifier sample and the second live emulsion are flowed is differentfrom a temperature at which the first demulsifier sample and the firstlive emulsion are flowed.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A pressure at which the seconddemulsifier sample and the second live emulsion are flowed is differentfrom a pressure at which the first demulsifier sample and the first liveemulsion are flowed.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. An image of the breakdown of the liveemulsion over time includes bubbles indicative of the breakdown. Thestrength of the live emulsion is classified based on sizes and densitiesof the bubbles in the image.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The live emulsion is formed by flowingthe hydrocarbon sample and the water sample through the capillaryviscometer, and applying a shear force to the hydrocarbon sample and thewater sample in the capillary viscometer to form the live emulsion.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A change in pressure across thecapillary viscometer over time resulting from the breakdown of the liveemulsion due to the demulsifier sample is measured. The strength of thelive emulsion is classified based, in part, on the change in thepressure across the capillary viscometer over time.

Certain implementations of the subject matter can be implemented as amethod. Multiple live emulsions are formed. Each live emulsion is formedfrom a live hydrocarbon sample and a water sample. Each live hydrocarbonsample includes dissolved gases retrieved from a hydrocarbon-carryingreservoir. Each live emulsion is flowed through a capillary viscometer.While flowing the live emulsion through the capillary viscometer, ademulsifier is injected into the capillary viscometer resulting in abreakdown of the live emulsion due to the demulsifier. Change in aviscosity of the live emulsion over time resulting from the breakdown ofthe live emulsion due to the demulsifier is measured. Change in apressure across the capillary viscometer over time resulting from thebreakdown of the live emulsion due to the demulsifier is measured.Multiple images of the breakdown of the live emulsion are captured overtime. The multiple live emulsions are classified according to respectivestrengths of the live emulsion based, in part, on the change in theviscosity measured, the change in the pressure measured and the multipleimages captured for each live emulsion.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. Each live emulsion is formed by flowinga mixture of the hydrocarbon sample and the water sample through thecapillary viscometer until a viscosity of the mixture substantiallystabilizes over time.

Certain implementations of the subject matter can be implemented as anapparatus including a viscometer and an imaging system. The viscometeris configured to flow at least one of a live emulsion formed from a livehydrocarbon sample, a water sample or a demulsifier sample configured tobreakdown a live emulsion formed by the live hydrocarbon sample and thewater sample. The live hydrocarbon sample includes dissolved gasesretrieved from a hydrocarbon-carrying reservoir. The viscometer isconfigured to measure change in a viscosity of the live emulsion overtime resulting from a breakdown of the live emulsion by the demulsifiersample. The imaging system is connected to the viscometer. The imagingsystem is configured to capture images or video of the breakdown of thelive emulsion by the demulsifier sample.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A first pump is fluidically connected toa first end of the viscometer. A second pump is fluidically connected toa second end, where the first and the second ends of the viscometer areopposing. The first pump and the second pump are configured to operatesynchronously to flow the live emulsion and the demulsifier multipletimes between the first end and the second end.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The viscometer includes a differentialpressure sensor connected to the viscometer. The differential pressuresensor is configured to sense a pressure differential across theviscometer due to the flow of the live emulsion of the demulsifierbetween the first end and the second end.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. An elongated tube is fluidicallyconnected to the viscometer. The elongated tube can flow the liveemulsion and the demulsifier sample. The elongated tube includes atransparent body.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The apparatus includes a viewing cellwithin which the elongated tube is positioned. The viewing cell and theimaging system are spatially positioned such that the imaging system isconfigured to capture the images or the video when the live emulsion andthe demulsifier sample flow through the elongated tube.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The imaging system includes a camera.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The imaging system includes amicroscope.

Certain aspects of the subject matter described here can be implementedas a method. A live emulsion of a live hydrocarbon sample and a watersample is flowed through a closed loop fluid flow system. The livehydrocarbon sample includes dissolved gases retrieved from ahydrocarbon-carrying reservoir. While flowing the live emulsion throughthe closed loop fluid flow system, a demulsifier sample is flowedthrough the closed loop fluid flow system. The demulsifier sample iscapable of breakdown of the live emulsion. Flow of a portion of amixture of the live emulsion and the demulsifier sample is isolated in aportion of the closed loop fluid flow system. Multiple images of thebreakdown of the live emulsion over time are captured within the portionof the closed loop fluid flow system. An effectiveness of thedemulsifier sample based, in part on the multiple images, is classified.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. To isolate flow of the portion of themixture in the portion of the closed loop fluid flow system, the portionof the mixture is flowed into the portion of the closed loop fluid flowsystem, and a first valve upstream of and a second valve downstream ofthe portion of the closed loop fluid flow system are closed.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. With the portion of the mixture isolatedin the portion of the closed loop fluid flow system, a remainder of themixture is continued to flow through a remainder of the closed loopfluid flow portion.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The remainder of the mixture is flowedthrough a capillary viscometer fluidically coupled in series with theremainder of the closed loop fluid flow system. Using the capillaryviscometer, change in a viscosity of the live emulsion over timeresulting from breakdown of the live emulsion due to the demulsifiersample is measured. The strength of the demulsifier is classified based,in part, on the change in the viscosity of the live emulsion over time.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The demulsifier sample is a firstdemulsifier sample. The live emulsion is a first live emulsion. A secondlive emulsion of the live hydrocarbon sample and the water sample isflowed through the closed loop fluid flow system. While flowing thesecond live emulsion through the closed loop fluid flow system, a seconddemulsifier sample is flowed through the closed loop fluid flow system.The second demulsifier sample is capable of breakdown of the liveemulsion. Flow of a portion of a mixture of the second live emulsion andthe second demulsifier sample is isolated in a portion of the closedloop fluid flow system. Multiple images of the breakdown of the secondlive emulsion over time within the portion of the closed loop fluid flowsystem are captured.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The effectiveness of the firstdemulsifier is further classified, based on the plurality of images ofthe breakdown of the second live emulsion over time.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A concentration of the seconddemulsifier sample is different from a concentration of the firstdemulsifier sample.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A temperature at which the seconddemulsifier sample and the second live emulsion are flowed is differentfrom a temperature at which the first demulsifier sample and the firstlive emulsion are flowed.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. A pressure at which the seconddemulsifier sample and the second live emulsion are flowed is differentfrom a pressure at which the first demulsifier sample and the first liveemulsion are flowed.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The live emulsion is formed by flowingthe hydrocarbon sample and the water sample through the closed loopfluid flow system, and applying a shear force to the hydrocarbon sampleand the water sample in the closed loop fluid flow system to form thelive emulsion.

Certain aspects of the subject matter described here can be implementedas a method. Multiple live emulsions are formed. Each live emulsion isformed from a live hydrocarbon sample and a water sample. The livehydrocarbon sample includes dissolved gases retrieved from ahydrocarbon-carrying reservoir. For each live emulsion, the liveemulsion is flowed through a closed loop fluid flow system. Whileflowing the live emulsion through the closed loop fluid flow system, ademulsifier sample is injected into the closed loop fluid flow system.The demulsifier sample is capable of breakdown of the live emulsion.Flow of a portion of a mixture of the live emulsion and the demulsifiersample in a portion of the closed loop fluid flow system is isolated.Multiple images of the breakdown of the live emulsion over time withinthe portion of the closed loop fluid flow system are captured. Aneffectiveness of the demulsifier sample is classified based, in part, onthe multiple images.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. To form each live emulsion, a mixture ofthe hydrocarbon sample and the water sample are flowed through theclosed loop fluid flow system until a viscosity of the mixturesubstantially stabilizes over time.

Certain aspects of the subject matter described here can be implementedas an apparatus. The apparatus includes a closed loop fluid flow systemincluding an elongated tube arranged as a closed loop. The apparatusincludes multiple containers coupled to the closed loop fluid flowsystem. The containers include a first container carrying livehydrocarbon comprising dissolved gases retrieved from ahydrocarbon-carrying reservoir, a second container carrying water, and athird container carrying a demulsifier configured to breakdown a liveemulsion formed by the live hydrocarbon and the water. The apparatusincludes a fluid flow system fluidically coupled to the closed loopfluid flow system and the multiple containers. The fluid flow system isconfigured to flow a live hydrocarbon sample from the first container, awater sample from the second container and a demulsifier sample from thethird container through the closed loop fluid flow system. The apparatusincludes an imaging system fluidically coupled to the closed loop fluidflow system. The imaging system is configured to capture images or videoof the breakdown of the live emulsion formed by the live hydrocarbonsample and the water sample by the demulsifier sample.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The fluid flow system includes a pumpfluidically connected in series to the multiple containers.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The apparatus includes a viewing cellwithin which a portion of the elongated tube is positioned. The viewingcell and the imaging system are spatially positioned such that theimaging system is configured to capture the images or the video when thelive emulsion and the demulsifier sample reside in the portion of theelongated tube.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The fluid flow system includes a firstvalve upstream of the viewing cell and a second valve downstream of theviewing cell. The first valve and the second valve are configured toisolate flow of a portion of a mixture of the live emulsion and thedemulsifier in the portion of the elongated tube within the viewingcell.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The imaging system includes a camera.

Aspects of the disclosure combinable with any of the other aspects caninclude the following features. The imaging system includes amicroscope.

The details of one or more implementations of the subject matterdescribed in this specification are set forth in the accompanyingdrawings and the description that follows. Other features, aspects, andadvantages of the subject matter will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an apparatus for evaluating demulsifiereffectiveness.

FIG. 2 is a flowchart of an example of a process for classifying livehydrocarbon liquid-water emulsions using the apparatus of FIG. 1.

FIG. 3A is a schematic diagram representing a strong emulsion.

FIG. 3B is a schematic diagram representing a medium-strength emulsion.

FIG. 3C is a schematic diagram representing a weak emulsion.

FIG. 4 is a schematic diagram of an apparatus for evaluating demulsifiereffectiveness.

FIG. 5 is a flowchart of an example of a process for classifying livehydrocarbon liquid-water emulsions using the apparatus of FIG. 4.

FIG. 6A is a schematic diagram of a live emulsion in a viewing cellbefore breakdown.

FIG. 6B is a schematic diagram of the live emulsion in the viewing cellduring breakdown.

FIG. 6C is a schematic diagram of the live emulsion in the viewing cellafter breakdown.

FIG. 7 is a plot comparing effectiveness of four demulsifiers.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

This disclosure describes methods and apparatuses to study the effect ofdemulsifiers on live emulsion samples.

In some implementations, an apparatus to implement the study includes aviscometer and a viewing cell connected in series and placed in atemperature-controlled environment. A live emulsion sample is introducedinto the viewing cell and the viscometer. Different quantities ofdemulsifiers are added to the live emulsion sample to break the samples.The viscosity of the sample-demulsifier mixture is measured using theviscometer, and images of the mixture are captured through the viewingcell. An effect of the varying quantities of the demulsifier on the liveemulsion sample are studied based on the viscosity measurements andusing the images. For example, a decrease in viscosity combined withvisual evidence of breakdown of the live emulsion indicates that ademulsifier is effective.

In some implementations, an apparatus to implement the study includes aclosed loop flow system and the viewing cell, both of which are placedin a temperature-controlled environment. A live emulsion sample isintroduced into the closed loop flow system and the viewing cell.Different quantities of demulsifiers are added to the live emulsionsample to break the sample. A quantity of the sample is statically heldwithin the viewing cell. The separation of the live emulsion sample intothe live hydrocarbon sample and water is imaged over time. An effect ofthe varying quantities on the live emulsion sample are studied based onresults of the imaging over time. For example, a first demulsifier isconsidered more effective than a second demulsifier if the firstdemulsifier causes breakdown of the live emulsion sample faster than thesecond demulsifier.

Implementing the techniques described in this disclosure can provideobjective and scientific observations about the effect of demulsifierson breakdown of live emulsions as opposed to subjective results obtainedfrom alternative techniques such as the bottle test. The techniquesdescribed in this disclosure test live samples under dynamic conditionsrather than dead samples tested under static conditions. In addition,the sample is tested under the temperature and pressure at which thesample is retrieved from the subsurface reservoir rocks or a processingfacility (for example, a temperatures ranging between 20 degreesCentigrade (° C.) and 150° C. and pressures ranging between 0 pounds persquare inch area (psia) and 5000 psia), which are different from roomtemperature and atmospheric pressure. Consequently, the effects of thedemulsifier on the sample as obtained by implementing the techniquesdescribed in this disclosure are more accurate and representativecompared to techniques in which the sample is tested at room temperatureor atmospheric pressure. The method avoids the artifacts of aging andexposure to air that can alter the properties of the crude oil and thelive emulsion.

At the outset, an emulsion sample is collected from subsurface reservoirrocks or a processing facility. For example, the entrapped hydrocarbonscan be produced through one or more production wellbores formed from thesubsurface reservoir rocks to the surface processing facilities. Asample of the produced live emulsion can be obtained at a location atwhich properties of the subsurface reservoir rocks are known or can bedetermined, for example, at a pre-determined depth from the surface atwhich the temperature and pressure can be measured. Alternatively, thesample can be obtained from a trunkline carrying the live emulsions tothe surface. In some implementations, the live emulsion with the livehydrocarbons obtained at the pre-determined depth, can be entrapped in asampling container. The sampling container can maintain the liveemulsion sample at the same conditions as the location from which thesample was obtained. The quantity of sample obtained can be sufficientto implement the techniques described later with reference to thefollowing figures. Such a sampling container can include valves andtubes that connect the container to the flowline through which thefluids are produced. The container can additionally be connected topressure gauges to monitor pressures of the fluids received in thesampling container and valves to control flow into or out of thecontainer.

Dynamic Classification

FIG. 1 is a schematic diagram of an apparatus 100 for evaluatingdemulsifier effectiveness. The apparatus 100 includes a capillaryviscometer 104 through which fluids, for example, a live emulsion sampleformed with live hydrocarbon and water, a demulsifier sample, or anycombination of them, can be flowed. Properties of the viscometer, forexample, dimensions such as length, inner diameter, outer diameter, andmaterial from which the viscometer is made, can be chosen to be suitableto implement the techniques described in this disclosure. For example,the viscometer can be made of stainless steel or similar material. Inone example, the viscometer can have an outer diameter of 6.35millimeters (mm), an inner diameter of 4.57 mm, a tube wall thickness of0.89 mm and a length of 6,096 mm. As explained earlier, in otherexamples, the viscometer can be made of other materials (for example,heat conducting materials with large tensile strength) or have otherdimensions or both.

A demulsifier is a chemical compound, for example, a mixture ofchemicals and surfactants, that can breakdown the live emulsion.Breakdown of the live emulsion is a separation, over time, of thehydrocarbon liquid sample and the water sample from each other intoseparate phases. Live emulsion breakdown is characterized by theaggregation of bubbles in a mixture of the live emulsion and thedemulsifier. Live emulsion texture (also known as bubble density) is aparameter for determining live emulsion strength and viscosity. Liveemulsion texture is defined as bubble size per unit volume. Small bubblesize or greater bubble density indicates high live emulsion strengthcompared to large bubble size or smaller bubble density which indicateslow live emulsion strength.

The apparatus 100 can be used to test the live emulsion describedearlier and to subsequently breakdown the live emulsion using ademulsifier. When the demulsifier breaks down the live emulsion , aviscosity of a mixture of the live emulsion and the demulsifier changes(for example, decreases) and bubbles form and propagate. The viscometer104 can be implemented to measure change in a viscosity of the liveemulsion over time resulting from a breakdown of the live emulsion bythe demulsifier.

The viscometer 104 can include two pumps (for example, reciprocatingpumps 110 a and 110 b) connected to the first end and the second end,respectively, of the viscometer 104. Each pump can be operatedsynchronously to flow the mixture of the live emulsion and thedemulsifier through the viscometer 104 such that one pump applies apositive pressure to push the mixture through the section while theother pump applies an equal and opposite negative pressure to draw themixture through the viscometer 104. After the mixture has flowed fromsubstantially one end of the viscometer 104 to the other end, then thepressures of the two pumps are reversed to cause the mixture to flowthrough the viscometer 104 in the opposite direction. The viscometer 104can be connected to a differential pressure sensor 112 that can measurethe differential pressure across the viscometer 104 resulting from thefluid flow.

The apparatus 100 includes a syringe pump 120 fluidically coupled inparallel with the reciprocating pumps. The syringe pump 120 can beimplemented to inject fluids (for example, demulsifiers) into thecapillary viscometer 104. For example, a fluid to be injected can beflowed using the syringe pump 120 into a fluid line that couples thesyringe pump 120 to one of the reciprocating pumps. Then, thereciprocating pumps can be operated in conjunction to flow the injectedfluid through the capillary viscometer 104.

The apparatus 100 also includes an imaging system connected to theviscometer 104. The imaging system can include a viewing cell 108 and acamera 105 or a microscope (or both) spatially arranged relative to theviscometer 104 to capture images or video of the breakdown of the liveemulsion caused by the demulsifier. In some implementations, the camera105 (or a microscope or both) can be positioned such that the viewfinderof the camera 105 is directed at the viewing cell 108. The camera 105can capture images or record video of the fluid flowing through theviewing cell 108. The camera 105 can be connected to a computer system109 that includes a user interface (for example, a computer monitor)connected to one or more processors and a computer-readable medium, forexample, a non-transitory computer-readable medium. The medium can storeinstructions executable by the one or more processors to perform some orall of the operations described in this disclosure. For example, theuser interface can display the images or video captured by the camera105. The computer system 109 can perform operations, for example, imageprocessing operations on the captured images or video. An elongated tubeconnected to the viscometer 104 can be positioned within the viewingcell 108. The elongated tube can have the same inner diameter as theviscometer 104 and can have a transparent body through which the liveemulsion flow and breakdown can be viewed or imaged or both. That is,only the length of the elongated tube which is positioned within theviewing cell 108 need be transparent.

In some implementations, the apparatus 100 can be positioned within atemperature-controlled housing 102, for example, an oven. By controllingthe temperature within the housing 102, and by controlling the pressurewith the pumps (110 a and 110 b), the techniques described in thisdisclosure can be implemented at temperatures and pressures that aresubstantially similar to the processing facilities or subsurfacereservoir rock conditions at which the live emulsions are formed. Forexample, the housing 102 can be operated at a temperature that is withina plus-or-minus 5% variation from a temperature of the subsurfacereservoir rock. The pumps 110 a and 110 b can be operated to apply apressure that is within a plus-or-minus 5% variation from a pressure ofthe subsurface rock.

FIG. 2 is a flowchart of an example of a process 200 for classifyingliquid-water live emulsions formed from live hydrocarbons. At 202,multiple live emulsions of live hydrocarbons and water are formed. To doso, a mixture of a live hydrocarbon sample and a water sample can beinjected into the viscometer 104, for example, using the syringe pump120 or one of the pumps 110 a or 110 b. The mixture of the livehydrocarbon sample and the water sample can be sheared, for example, byflowing the mixture back and forth multiple times through the viscometer104, to form the live emulsion. To do so, in some implementations, thetwo pumps 110 a, 110 b can be operated synchronously, as describedearlier. In some implementations, the live emulsion can be formedseparately, that is, outside the viscometer 104.

At 204, the live emulsion is flowed through the viscometer. In examplesin which the live emulsion is formed within the capillary viscometer104, the pumps can be operated to flow the live emulsion. In examples inwhich the live emulsion is formed outside the viscometer 104, the liveemulsion can be injected into the capillary viscometer 104 using thesyringe pump 120. In this manner, after forming the live emulsion, apre-determined quantity of the live emulsion can be flowed through theviscometer 104. The pre-determined quantity of the live emulsion andthose of other fluids to be injected into the viscometer 104 can bechosen based on factors including the inner volume of the viscometer104. One or both of the pumps 110 a, 110 b can be operated to flow thelive emulsion through the viscometer 104 at pre-determined pressures.The pressure in the system is set by the pump and can vary fromatmospheric to the maximum allowable working pressure of the viscometer104 and the viewing cell 108 (up to several thousand pounds per squareinch).

At 206, a demulsifier is added to the viscometer. For example, afterflowing the pre-determined quantity of the live emulsion into theviscometer 104, a pre-determined quantity of a demulsifier can beinjected into the viscometer 104, for example, using the syringe pump120, to mix with the live emulsion. The demulsifier can breakdown thelive emulsion, that is, separate, the live hydrocarbon sample and thewater sample. Examples of demulsifiers include those formulated withpolymeric chains of one of ethylene oxides and polypropylene oxides ofalcohol, ethoxylated phenols, ethoxylated alcohols and amines,ethoxylated resins, ethoxylated nonylphenols, polyhydric alcohols, orsulphonic acid salts. The concentration of the demulsifier can bedetermined based on the demulsifier type and its effectiveness inbreaking down the live emulsion. For example, the demulsifierconcentrations can range from less than 5 parts per million (ppm) byvolume, which is approximately 1 gallon (gal) per 5,000 barrels (bbls)to more than 200 ppm (approximately 8 gal/1,000 bbls). For example, thequantity of the demulsifier can range between 10 ppm and 50 ppm. Ingeneral, the quantity of the demulsifier can be sufficient to diffusethe oil-water interface of the live emulsion but not greater than thecritical aggregate micelle concentration. As described later, theseparation of the hydrocarbon liquid sample-water live emulsion overtime in response to adding the demulsifier is monitored.

At 208, a change in viscosity of the mixture of the live emulsion andthe demulsifier is measured. For example, the viscometer 104 can be usedto measure the viscosity of the mixture of the live emulsion and thedemulsifier. To do so, the two pumps 110 a, 110 b are operatedsynchronously, as described earlier, causing the mixture of the liveemulsion and the demulsifier to flow back and forth in the viscometer104. As the demulsifier breaks down the live emulsion during thesynchronous flow, the viscosity of the mixture and its rheology changeover time. Most live emulsions are classified as non-Newtonian fluidswhose apparent viscosity depends on shear rate (γ), which induces ashear stress (τ) in the flowing fluid. Apparent viscosity (μ_(apparent))is determined according to Eqs. 1-3.

$\begin{matrix}{\mu_{apparent} = \frac{\tau}{\gamma}} & \left( {{Eq}.\mspace{14mu} 1} \right) \\{\tau = \frac{D\Delta P}{4L}} & \left( {{Eq}.\mspace{14mu} 2} \right) \\{\gamma = \frac{8V}{D}} & \left( {{Eq}.\mspace{14mu} 3} \right)\end{matrix}$

In Eqs. 2 and 3,D is the diameter of the viscometer 104, AP is thepressure drop across the viscometer 104 measured, for example, using thepressure sensor 112, L is the length of the viscometer, and Vis thefluid flow velocity. To measure the viscosity at a time instant, thepressure drop across the viscometer 104 at a fixed shear rate in eitherdirection is measured using the differential pressure sensor 112. Themeasurement is repeated at multiple time instants. The duration betweentwo time instants can be sufficient for the viscosity to stabilizeduring that interval. By stabilizing of viscosity over time, it is meantthat a rate of change of the viscosity over time is less than athreshold change. For example, when a slope of a plot of viscosity overtime is close to zero (such as less than 1 or 2), then the viscosity isconsidered as having stabilized. Eqs. 1-3 can be solved, for example,using the computer system 109.

In some implementations, Eqs. 1-3 are applied to determine the viscosityat each time instant. In some implementations, the pressure drop can bemeasured multiple times between two time instants and a viscositydetermined for each measured pressure drop. An average viscosity betweentwo time instants can be determined. By measuring viscosity over time, aviscosity profile, that is, a plot of viscosity over time, can bedeveloped for the mixture of the live emulsion and the demulsifier. Asthe demulsifier breaks down the live emulsion over time, the viscosityof the mixture will decrease. Once the live emulsion has broken down,the viscosity will remain substantially steady.

At 210, multiple images of the breakdown of the live emulsion over timeare captured. The images can be static images or video. As thedemulsifier breaks down a live emulsion, small bubbles begin to coalesceinto larger bubbles in the mixture of the live emulsion and thedemulsifier. The texture of the live emulsion changes as the bubble sizeand coalescence takes place. Live emulsion texture is a parameter usedto determine live emulsion strength and viscosity. Live emulsiontexture, also known as bubble density, is defined as bubble size perunit volume. There is an inverse relationship between bubble density andbubble size. The apparent viscosity of a live emulsion depends on thelive emulsion texture. Smaller bubbles indicate higher apparentviscosity and vice versa.

FIG. 3A is a schematic diagram 302 of a live emulsion. The schematicdiagram 302 represents an image captured at a time instant before addinga demulsifier to a live emulsion. The bubbles are indicative of thetightness of the live emulsion. After adding the demulsifier, the imagesof the live emulsions are captured over time. In some implementations,multiple images of the breakdown can be captured over time. For example,an image can be captured each time a pressure drop is measured.Alternatively or in addition, an image can be captured each time anaverage viscosity is determined. The bubble size and bubble density inthe images will change over time reflecting the breakdown of the liveemulsion by the demulsifier. After a while, the breakdown reaches steadystate following which the bubble size and bubble density in the imageswill remain substantially unchanged.

Back to FIG. 2, at 212, the live emulsion is classified. For example,the live emulsion can be classified as a strong live emulsion, amedium-strength live emulsion or a weak live emulsion based, in part, onbubble size and bubble density. The schematic diagram 302 (FIG. 3A) isrepresents a strong live emulsion. The schematic diagram 304 (FIG. 3B)represents a medium-strength live emulsion because the bubble size isgreater than that of schematic diagram 302 and the bubble density isless than that of the schematic diagram 302. The schematic diagram 306(FIG. 3C) represents a weak live emulsion because the bubble size isgreater than that of the schematic diagram 304 and the bubble density isless than that of the schematic diagram 304.

In some implementations, the classification of the live emulsion basedon the image can be performed manually or using computer-implementedsoftware or both. For example, the computer software can receive, asinput, a portion of the live emulsion image that includes bubbles andreturn, as output, a histogram showing a range of sizes of the bubblesin the image.

In some implementations, an effectiveness of the demulsifier tobreakdown the live emulsion can also be classified based, in part, onthe viscosity profile and the images. For example, if the viscosityprofile shows a drop in viscosity over a short duration for a stronglive emulsion whose images have small bubble size or large bubbledensity, then the demulsifier has a greater effectiveness. Conversely,if the viscosity profile shows a drop in viscosity over a comparativelylong duration for a weak live emulsion whose images have a comparativelylarge bubble size or a comparatively low bubble density, then thedemulsifier has a comparatively poorer effectiveness.

Static Classification

FIG. 4 is a schematic diagram of an apparatus 400 for evaluatingdemulsifier effectiveness. The apparatus 400 includes a closed loopfluid flow system 402 through which fluids, for example, a livehydrocarbon sample, water, an emulsion formed of the two, a demulsifier,or any combination of them, can be flowed. In some implementations, theclosed loop fluid flow system 402 is an elongated tube, for example, acapillary tube similar to that used with the capillary viscometer 104described earlier. The apparatus 400 includes multiple containers (forexample, containers 404 a, 404 b, 404 c) fluidically coupled to theclosed loop fluid flow system 402. For example, each container can befluidically coupled to the capillary tube to reside outside the closedloop and to inject fluid carried by the container into the closed loop.For example, container 404 a, container 404 b and container 404 c cancarry live hydrocarbon, water and demulsifier, respectively. Thedemulsifier can be similar to the demulsifier described earlier withreference to apparatus 100. In some implementations, the volume of theflow system 402 can be between 250 milliliters (ml) and 300 ml, forexample, 260 ml.

In some implementations, a valve 406 a, a valve 406 b and a valve 406 ccan regulate flow of the fluid carried by the container 404 a, thecontainer 404 b and the container 404 c into the capillary tube. Forexample, each container can be fluidically coupled to a respective pump(not shown) to draw fluids from the container and to flow the drawnfluids into the closed loop flow system 402 when the corresponding valveis in an open state. Subsequently, the corresponding valve can be closedand remain closed to prevent fluid from the container from flowing intothe closed loop fluid flow system 402 and vice versa. In someimplementations, fluids from the containers injected into the closedloop fluid flow system 402 can be flowed through the system 402 by afluid flow system 408. For example, the fluid flow system 408 caninclude a circulation pump fluidically coupled in-line with thecapillary tube. One or more of the valves 406 a, 406 b or 406 c can beplaced in an open state, and the pump operated to draw pre-determinedvolumes of fluids from the respective containers into the capillarytube. Subsequently, the opened valves can be transitioned to a closedstate, and the pump operated to flow fluids through the capillary tube.

In some implementations, an imaging system 414 can be fluidicallycoupled to the closed loop fluid flow system 402. For example, theimaging system 414 can include a viewing cell 412 and a camera 414 or amicroscope (or both) spatially arranged relative to the viewing cell 412to capture images or video of the breakdown of the live emulsion causedby the demulsifier. The viewing cell 412 can be partially or entirelytransparent. In some implementations, the camera 414 (or a microscope orboth) can be positioned such that the viewfinder of the camera 414 isdirected at the viewing cell 412. The camera 414 can capture images orrecord video of the fluid residing in the viewing cell 12. As describedlater, breakdown of the live emulsion in the viewing cell 412 manifestsas a separation of the live hydrocarbon and the water. The camera 414can be positioned to image the separation. For example, as the livehydrocarbon and the water separate due to breakdown of the emulsion, theheavier of the two fluids can settle to the bottom of the viewing cell412 and the lighter of the two fluids can rise to the top of the viewingcell 412. The camera 414 can be positioned relative to the viewing cell412 to image and capture the separation of the two fluids.

The camera 414 can be connected to a computer system 416 that includes auser interface (for example, a computer monitor) connected to one ormore processors and a computer-readable medium, for example, anon-transitory computer-readable medium. The medium can storeinstructions executable by the one or more processors to perform some orall of the operations described in this disclosure. For example, theuser interface can display the images or video captured by the camera414. The computer system 416 can perform operations, for example, imageprocessing operations on the captured images or video.

In some implementations, a valve 418 a and a valve 418 b can befluidically coupled to the closed loop fluid flow system 402 upstreamand downstream, respectively, of the viewing cell 412. The two valvescan isolate flow of a portion of fluid in the viewing cell 412. That is,the upstream valve 418 a can be in an open state and the downstreamvalve 418 b can be in a closed state to permit fluid flowing through theclosed loop fluid flow system 402 to accumulate in the viewing cell 412.Once the viewing cell 412 has been filled to a pre-determined level,then both valves can be in a closed state, thereby isolating the fluidin the viewing cell 412 from the remainder of the fluid in the closedloop fluid flow system 402. In some implementations, the apparatus 400can be positioned within a temperature-controlled housing 420, forexample, an oven.

In some implementations, an emulsion-generating shear device 410 can befluidically coupled to the closed loop fluid flow system 402. Forexample, the device 410 can receive a live hydrocarbon sample and awater sample, and apply shear to the two to form the emulsion. In someimplementations, the emulsion is formed by applying shear with thedevice 410 and flowing the mixture through the flow system 402 to formthe live emulsion. For example, the mixture can be flowed through theclosed loop of the flow system 402, multiple times to form the liveemulsion. The flow pressure of the mixture can vary from a time when thelive hydrocarbon and the water are flowed to when the live emulsion isformed. In some implementations, a differential pressure sensor (notshown) can be fluidically coupled to the flow system 402 to measure theflow pressure of the mixture. When the differential pressure stabilizesover time, then it can be concluded that the live emulsion has formed.By stabilizing of pressure over time, it is meant that a rate of changeof the pressure over time is less than a threshold change. For example,when a slope of a plot of pressure over time is close to zero (such asless than 1 or 2), then the pressure is considered as having stabilized.

The apparatus 400 can be implemented to characterize the effectivenessof demulsifiers in demulsification of oil-water emulsions. For example,a pre-determined volume of live hydrocarbons and water are drawn fromtheir respective containers and injected into the closed loop fluid flowsystem 402. The pump 408 flows the pre-determined volumes either at roomtemperature or at a pre-determined temperature regulated using thehousing 420. The device 410 applies shear to and mixes the livehydrocarbons and water to form a live emulsion. The device 410 can beoperated at a shear rate that is similar to the shear rate experiencedby the live hydrocarbons and water when flowed through a productiontubing or flow line. Then, a pre-determined volume of demulsifier isdrawn from its respective container and injected into the closed loopfluid flow system 402. The device 420 mixes the demulsifier with theemulsion causing a breakdown of the emulsion. The pump 408 flows aportion of the mixture into the viewing cell 412 at which time the twovalves 418 a and 418 b are transitioned to a closed state to isolate thefluid in the viewing cell 412. The imaging system 414 is operated toimage the breakdown of the emulsion over time in the viewing cell 412.The process can be repeated for different concentrations of demulsifier,and the results compared to determine a quantity of demulsifier that iseffective for demulsification of a live emulsion. The process can alsobe repeated at different process conditions, for example, differentconcentrations of live hydrocarbon or water to form live emulsions,different types of demulsifiers, different temperatures or pressures, orany combination of them. After breakdown of the live emulsion has beenimaged under one or one set of process conditions, the fluids in theclosed loop fluid flow system 402 can be drained, for example, throughthe drain line 422, and new fluids under new process conditions can beintroduced for further evaluation.

FIG. 5 is a flowchart of an example of a process 500 for classifyinglive hydrocarbon liquid-water emulsions using the apparatus of FIG. 4.At 502, multiple live emulsions of live hydrocarbons and water areformed. To do so, a mixture of a live hydrocarbon sample and a watersample are drawn into the closed loop fluid flow system 402, forexample, using pumps fluidically coupled to the containers carrying thesamples. The device 410 can shear the samples and the pump 408 can flowthe sheared mixture through the flow system 402 until the emulsion isformed. Different types of live emulsions can be formed by varying thequantities of the live hydrocarbon and water.

At 504, the live emulsion is flowed through the closed loop fluid flowsystem 402, for example, the capillary tube. For example, the pump 408can flow the live emulsion through the closed loop of the flow system402. In some implementations, the process conditions under which thelive emulsion is flowed through the flow system 402 can be controlled.For example, the housing 420 can be operated to apply a range oftemperatures to the live emulsion. Alternatively or in addition, thepump 408 can be operated to apply a range of pressures to the liveemulsion. The process conditions can be selected to match subsurfacereservoir conditions where hydrocarbons with the live emulsions arefound or the flowline conditions through which hydrocarbons with thelive emulsions are flowed.

At 506, a demulsifier is added to the capillary tube. For example, afterflowing the pre-determined quantity of the live emulsion through theflow system 402, a pre-determined quantity of a demulsifier can be drawnfrom its container and injected into the capillary tube. Flowing thelive emulsion and the demulsifier in the capillary tube can cause thetwo fluids to mix, thereby initiating breakdown of the live emulsion. Insome implementations, the device 410 can be operated to apply shear tothe mixture to increase the speed of mixing and breakdown initiation.The types of demulsifiers and concentrations of the same can be similarto those described earlier with reference to FIG. 2.

At 508, a portion of a mixture of the live emulsion and the demulsifieris received in the viewing cell. For example, the pump 408 flows themixture of the live emulsion and the demulsifier into the viewing cell412 in which the mixture accumulates. The viewing cell 412 can have avolume in the order of milliliters (ml), for example, less than 100 ml.In some implementations, an entirety of the viewing cell 412 is filledwith the mixture of the live emulsion and the demulsifier. In someimplementations, a portion (for example, one-half and two-thirds) of theviewing cell 412 is filled with the mixture. The portion in the viewingcell 412 is isolated by closing the valves 418 a and 418 b. Onceisolated, the portion in the viewing cell is static. That is, notadditional force or pressure is applied on the portion in the viewingcell 412. In some implementations, the pump 408 and the device 410 canbe turned off to not apply the additional force or pressure to theportion in the viewing cell 412.

At 510, separation of live hydrocarbon and water over time is imaged inthe viewing cell. Breakdown of the live emulsion due to the demulsifierresults in separation of the live emulsion into live hydrocarbon andwater. The immiscibility of the live hydrocarbon and water result in theheavier fluid settling to the bottom of the viewing cell 412 and thelighter fluid rising to the top of the viewing cell 412. Alternativelyor in addition, the breakdown of the live emulsion due to thedemulsifier results in the formation of bubbles. As breakdown continuesover time, smaller bubbles coalesce to form larger bubbles indicatingfurther separation. The camera 414 captures the breakdown, for example,the separation or the coalescing or both. For example, the camera 414can capture video of the separation and coalescing over time.Alternatively or in addition, the camera 414 can periodically captureimages of the separation and coalescing. The camera 414 can transfer theresults of the imaging (that is, the videos or the images) to thecomputer system 416 for storage and further analysis

FIG. 6A is a schematic diagram of a live emulsion in a viewing cell (forexample, the viewing cell 412) before breakdown. FIG. 6B is a schematicdiagram of the live emulsion in the viewing cell during breakdown. FIG.6C is a schematic diagram of the live emulsion in the viewing cell afterbreakdown The diagrams schematically show the separation of the liveemulsion into the live hydrocarbon and water. Before breakdown (FIG.6A), the entire portion in the viewing cell 412 consists of the liveemulsion. During breakdown (FIG. 6B), some water, having separated fromthe live emulsion, settles to the bottom of the viewing cell 412. Afterbreakdown (FIG. 6C), all water in the live emulsion settles to thebottom while all live hydrocarbon in the live emulsion has risen to thetop of the viewing cell 412.

Back at FIG. 5, at 512, the demulsifier is classified. For example, thedemulsifier can be classified based on its effectiveness to breakdownand separate the live emulsion into the live hydrocarbon and water. Todo so, the results of imaging the breakdown using the imaging system 414can be examined to determine a time taken by a demulsifier to breakdownand separate the live emulsion. The examination can be performedmanually. Alternatively, or in addition, the computer 419 can beprogrammed to perform the examination without user intervention. In oneexample, if the time taken by a first demulsifier to breakdown andseparate a live emulsion under certain process conditions is less thanthe time by a second demulsifier to breakdown and separate the liveemulsion under the same process conditions, then the first demulsifierhas a greater effectiveness than the second demulsifier at those processconditions. In another example, if the time taken by a demulsifier tobreakdown and separate a live emulsion under a first set of processconditions is less than the time taken by the same demulsifier tobreakdown and separate the live emulsion under a second set of processconditions different from the first, then the demulsifier has a greatereffectiveness at the first set of process conditions than the second.The process conditions can include a quantity of each of the livehydrocarbon and water used to form the live emulsion, processtemperature or pressure (or both) or similar conditions. FIG. 7 is aplot 700 comparing effectiveness of four demulsifiers. The processconditions for the comparison are the following—temperature=120 degreesFahrenheit (° F.), pressure=100 pounds per square inch (psi),demulsifier concentration=25 parts per million by volume, water cut=25%.The X-axis and Y-axis show separation time (in minutes) and waterseparation (in percentage) for each of the four demulsifiers.

The earlier portions of the disclosure described apparatuses andtechniques to determine a strength of a live emulsion and of theeffectiveness of a demulsifier to breakdown that live emulsion. Thetechniques can be repeated to determine the strength of multipledifferent live emulsions and of the effectiveness of either multiple,different demulsifiers or of the same demulsifier at different reservoiror processing conditions, for example, temperatures and pressures, or atdifferent concentrations, or both. For example, in a first test, apre-determined quantity of the live emulsion and a pre-determinedquantity of the demulsifier can be tested as described earlier. In asecond test, the same quantity of the live emulsion and a differentquantity of the demulsifier (for example, one-half of or twice or threetimes) can be tested as described earlier. By repeating the test withdifferent concentrations of the demulsifier, the effectiveness of thevarying concentrations of the demulsifier on the breakdown of the liveemulsion as well as strength of the live emulsion under the varyingconcentrations of the demulsifier can be determined.

In another example, in a first test, a pre-determined quantity of thelive emulsion and a pre-determined quantity of the demulsifier can betested at a first temperature as described earlier. In a second test,the same quantity of the live emulsion and the same quantity of thedemulsifier can be tested at a second temperature different from thefirst temperature. By repeating the test at different temperatures, theeffectiveness of the same quantity of the demulsifier at differenttemperatures on the breakdown of the live emulsion as well as strengthof the live emulsion under the different temperatures can be determined.

In a further example, in a first test, a pre-determined quantity of thelive emulsion and a pre-determined quantity of the demulsifier can betested at a first pressure as described earlier. In a second test, thesame quantity of the live emulsion and the same quantity of thedemulsifier can be tested at a second pressure different from the firstpressure. By repeating the test at different pressures, theeffectiveness of the same quantity of the demulsifier at differentpressures on the breakdown of the live emulsion as well as strength ofthe live emulsion under the different pressures can be determined.Similar tests can be performed by varying more than one test condition,for example, type of demulsifier, concentration of emulsifier, flowtemperature, and flow pressure. Similar tests can also be performed byvarying the initial concentration of the hydrocarbon liquid sample orthe water sample (or both), or by varying the aging time to formdifferent types of live emulsions to be tested. The output of the testscan be compiled to produce reference material (for example, tables,spreadsheets, or the like) that identify the conditions under which thelive emulsions were formed, the information directed to the demulsifiersthat were used to test the live emulsions and the process conditions(that is, temperatures, pressures) under which the tests were performed.

As described earlier, the apparatus 100 (FIG. 1) can be implemented toperform dynamic operations and the apparatus 400 (FIG. 4) can beimplemented to perform static operations, both to evaluate theeffectiveness of demulsifiers and strength of live emulsions. Componentsof the two apparatuses can be interchangeably used. For example,components used in the apparatus 100 can be similar or identical tothose used in the apparatus 400 permitting the interchangeable use.

In some implementations, an apparatus that combines features of theapparatus 100 (FIG. 1) and the apparatus 400 (FIG. 4) can be constructedto perform the dynamic and static operations simultaneously. To do so,components described earlier with reference to each apparatus can becombined or re-purposed. For example, the sample carrying containers 404a, 404 b, 404 c of the apparatus 400 (FIG. 4) can be fluidically coupledto the synchronous pumps 110 a, 110 b of the apparatus 100 (FIG. 1) toallow pre-determined quantities of each fluid drawn from each of thecontainers 404 a, 404 b, 404 c to be injected into the capillaryviscometer 104. In addition, the portion of the closed loop fluid flowsystem 402 in which the portion of the mixture of the live emulsion andthe demulsifier is isolated (that is, the viewing cell 412 with theupstream and downstream valves 418 a, 418 b) can be fluidically coupledin parallel to the capillary viscometer 104. In such an arrangement, thecombined apparatus can be operated such that the change in the viscosityof a first portion of the mixture of the live emulsion and thedemulsifier can be viewed in the viewing cell 108 (FIG. 1) at the sametime that the separation of a second portion of the mixture of the liveemulsion and the demulsifier is viewed in the viewing cell 412 (FIG. 4).Alternatively or in addition, the combined apparatus can also beoperated to perform either the dynamic operations or the staticoperations independently. With such an arrangement, the effectiveness ofthe demulsifiers and the strength of the emulsion can be determinedbased on the change in the viscosity of and the bubble densities ofimages of the mixture of the live emulsion and demulsifier, as well asthe time for separation of the live emulsion into the live hydrocarbonand water.

In some implementations, the operations described in this disclosure,for example, the control of any component of any apparatus or theanalysis of the information captured by the information systems, can beperformed by a controller operatively coupled to the apparatus,particularly, to each component of the apparatus. The controller can beimplemented as a computer system including one or more processors and acomputer-readable medium storing instructions executable by the one ormore processors to perform the operations in this disclosure. In someimplementations, the controller can be configured to perform multipleoperations in any sequence, for example, in parallel or in series. Forexample, the controller can be programmed to implement an automatedsequence of operations to classify multiple, different live emulsions ormultiple, different emulsifiers or combinations of them. The controllercan select pre-determined, different concentrations of live hydrocarbonsand water to form multiple, different live emulsions. The controller canapply multiple, different process conditions to the live emulsions. Thecontroller can select pre-determined, different types or concentrations(or both) of demulsifiers to mix with the live emulsions. The controllercan operate the imaging systems to image the breakdown of the liveemulsions, store the imaging information and perform classificationoperations. In particular, the controller can perform the describedoperations without user intervention.

Determining live emulsion strength and the effectiveness of demulsifiersat different conditions to breakdown live emulsions can allowcontrolling operations such as hydrocarbon processing operationsimplemented as GOSPs. For example, live emulsions in producedhydrocarbons can be broken down by adding pre-determined quantities ofdemulsifiers at known process conditions (that is, temperatures,pressures) to effectively break down the live emulsions. In particular,the reference material can be used to identify the optimal demulsifierand the optimal process conditions to breakdown different types of liveemulsions in the produced hydrocarbons.

Thus, particular implementations of the subject matter have beendescribed. Other implementations are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results. Inaddition, the processes depicted in the accompanying figures do notnecessarily require the particular order shown, or sequential order, toachieve desirable results. In certain implementations, multitasking andparallel processing may be advantageous.

1. A method comprising: flowing a live emulsion of a live hydrocarbonsample and a water sample through a capillary viscometer, wherein thelive hydrocarbon sample comprises dissolved gases retrieved from ahydrocarbon-carrying reservoir; while flowing the live emulsion throughthe capillary viscometer, flowing a demulsifier sample through thecapillary viscometer, wherein the demulsifier sample is capable ofcausing breakdown of the live emulsion; measuring, using the capillaryviscometer, change in a viscosity of the live emulsion over timeresulting from the breakdown of the live emulsion due to the demulsifiersample; capturing a plurality of images of the breakdown of the liveemulsion over time; and classifying a strength of the live emulsionbased, in part, on the change in the viscosity of the live emulsion overtime and on the plurality of images.
 2. The method of claim 1, whereinthe demulsifier sample is a first demulsifier sample and the liveemulsion is a first live emulsion, wherein the method further comprises:flowing a second live emulsion of the hydrocarbon sample and waterthrough the capillary viscometer; while flowing the second live emulsionthrough the capillary viscometer, flowing a second demulsifier samplethrough the capillary viscometer, wherein the second demulsifier samplecauses breakdown of the second live emulsion; measuring, using thecapillary viscometer, change in a viscosity of the second live emulsionover time resulting from the breakdown of the second live emulsion dueto the second demulsifier sample; and capturing a plurality of images ofthe breakdown of the second live emulsion over time.
 3. The method ofclaim 2, wherein the strength of the live emulsion is furtherclassified, in part, based on the change in the viscosity of the secondlive emulsion over time and on the plurality of images of the breakdownof the second live emulsion over time.
 4. The method of claim 2, whereina concentration of the second demulsifier sample is different from aconcentration of the first demulsifier sample.
 5. The method of claim 2,wherein a temperature at which the second demulsifier sample and thesecond live emulsion are flowed is different from a temperature at whichthe first demulsifier sample and the first live emulsion are flowed. 6.The method of claim 2, wherein a pressure at which the seconddemulsifier sample and the second live emulsion are flowed is differentfrom a pressure at which the first demulsifier sample and the first liveemulsion are flowed.
 7. The method of claim 1, wherein an image of thebreakdown of the live emulsion over time comprises bubbles indicative ofthe breakdown, wherein the strength of the live emulsion is classifiedbased on sizes and densities of the bubbles in the image.
 8. The methodof claim 1, further comprising forming the live emulsion by: flowing thehydrocarbon sample and the water sample through the capillaryviscometer; and applying a shear force to the hydrocarbon sample and thewater sample in the capillary viscometer to form the live emulsion. 9.The method of claim 1, further comprising measuring a change in pressureacross the capillary viscometer over time resulting from the breakdownof the live emulsion due to the demulsifier sample, wherein the strengthof the live emulsion is classified based, in part, on the change in thepressure across the capillary viscometer over time.
 10. A methodcomprising: forming a plurality of live emulsions, each live emulsionformed from a LIVE hydrocarbon sample and a water sample, wherein eachlive hydrocarbon sample comprises dissolved gases retrieved from ahydrocarbon-carrying reservoir; for each live emulsion: flowing the liveemulsion through a capillary viscometer, while flowing the live emulsionthrough the capillary viscometer, injecting a demulsifier into thecapillary viscometer resulting in a breakdown of the live emulsion dueto the demulsifier, measuring change in a viscosity of the live emulsionover time resulting from the breakdown of the live emulsion due to thedemulsifier, measuring change in a pressure across the capillaryviscometer over time resulting from the breakdown of the live emulsiondue to the demulsifier, and capturing a plurality of images of thebreakdown of the live emulsion over time; and classifying the pluralityof live emulsions according to respective strengths of the live emulsionbased, in part, on the change in the viscosity measured, the change inthe pressure measured and the plurality of images captured for each liveemulsion.
 11. The method of claim 10, wherein forming the plurality oflive emulsions comprises, for each live emulsion, flowing a mixture ofthe hydrocarbon sample and the water sample through the capillaryviscometer until a viscosity of the mixture substantially stabilizesover time.
 12. An apparatus comprising: a viscometer configured to: flowat least one of a live emulsion of a live hydrocarbon sample, a watersample or a demulsifier sample configured to breakdown a live emulsionformed by the live hydrocarbon sample and the water sample, wherein thelive emulsion comprises dissolved gases retrieved from ahydrocarbon-carrying reservoir, and measure change in a viscosity of thelive emulsion over time resulting from a breakdown of the live emulsionby the demulsifier sample; and an imaging system connected to theviscometer, the imaging system configured to capture images or video ofthe breakdown of the live emulsion by the demulsifier sample.
 13. Theapparatus of claim 12, further comprising: a first pump fluidicallyconnected to a first end of the viscometer; and a second pumpfluidically connected to a second end of the viscometer opposite thefirst end, wherein the first pump and the second pump are configured tooperate synchronously to flow the live emulsion and the demulsifier aplurality of times between the first end and the second end.
 14. Theapparatus of claim 13, wherein the viscometer comprises a differentialpressure sensor connected to the viscometer, the differential pressuresensor configured to sense a pressure across the viscometer due to theflow of the live emulsion of the demulsifier between the first end andthe second end.
 15. The apparatus of claim 12, further comprising anelongated tube fluidically connected to the viscometer, the elongatedtube configured to flow the live emulsion and the demulsifier sample,the elongated tube comprising a transparent body.
 16. The apparatus ofclaim 15, further comprising a viewing cell within which the elongatedtube is positioned, the viewing cell and the imaging system spatiallypositioned such that the imaging system is configured to capture theimages or the video when the live emulsion and the demulsifier sampleflow through the elongated tube.
 17. The apparatus of claim 12, whereinthe imaging system comprises a camera.
 18. The apparatus of claim 12,wherein the imaging system comprises a microscope.